Plywood for concrete forms

[Deere Dude]

I am not a chemist like everyone else on this spiraling out of control thread, but I put a roof on a storm shelter located in my garage. I used 3/4 treated plywood and after a little bracing I poured an 8" thick x 8'x8' slab as the roof. There was no way to get the plywood out after the fact. It has been 3 years and still looks like new. I did throw some screws into the wood to hold it to the concrete just in case it would sag in the center.

 

[ovrszd]

Mab, this got stupid

Intellectually so.

 

[downsizingnow48]

It takes a lot of bracing to form a wall using plywood.

 

[Wood_Butcher_Dav]

I used sub-floor material as the bottom of my concrete storm shelter roof.


Dave

 

[Deere Dude]

It takes a lot of bracing to form a wall using plywood.

After building a small number of walls using 20 sheets plywood and having to buy tons of 2x4s I found out that every piece of wood got sucked into the system anyway. A lot got reused for other concrete walls, a lot got used for shelving in the garage and barn. It all got used up someplace else so it was not all money down the drain.

 

[downsizingnow48]

After building a small number of walls using 20 sheets plywood and having to buy tons of 2x4s I found out that every piece of wood got sucked into the system anyway. A lot got reused for other concrete walls, a lot got used for shelving in the garage and barn. It all got used up someplace else so it was not all money down the drain.

Yep it can be used again definitely. Also, other side of the formed wall looks the same. With lots of form ties to hold them together. Just wanted to offer OP an idea what is involved. Concrete will bulge or even knock down the form if given a chance. Better safe than sorry.

 

[turnkey4099]

It takes a lot of bracing to form a wall using plywood.

Or cross ties between the walls, Forms for my patio retaining wall (6!x4'x24' consisted of 2x4 lengthwise top and bottom, a few vertical 2x4 and a lot of 'snap off' cross ties.

 

[bunyip]

We have a product called Formply, it is a black coated plywood designed for concrete formwork, I'm sure you would have the same thing but probably with a different name.
Have used this for various tasks not relating to concrete and the last one was for a new ramp on a horse float.

 

[downsizingnow48]

Or cross ties between the walls, Forms for my patio retaining wall (6!x4'x24' consisted of 2x4 lengthwise top and bottom, a few vertical 2x4 and a lot of 'snap off' cross ties.

Yes to snap ties. The photo I put up shows lots of snap ties connecting the walers.

 

[Streetcar]

I think you just made Snobdds point.

SnobDds is completely wrong. Rock crawler is correct, the cement hydrates in the concrete while water is incorporated in the new compound. Water does not evaporate, except the excess which is not needed in the chemical reaction